With the advent of 3G era, mobile communications have fully come into 3G era. Currently, there are three 3 G communication standards in the world, which are respectively wideband code division multiple access (WCDMA), code division multiple access 2000 (CDMA2000), and time division-synchronized code division multiple access (TD-SCDMA). TD-SCDMA is an international standard proposed by China and recognized by the International Telecom Standardization Organization, and China possesses the core proprietary intellectual property rights. Currently, China mobile TD-SCDMA network has obtained 85 MHz frequency accumulatively, which are respectively 20 MHz (1880-1900 MHz) in F band, 15 MHz (2010-2025 MHz) in A band and 50 MHz (2320-2370 MHz) in E band, wherein E band now is merely allowed to be used for indoor coverage.
However, since the current TD-SCDMA network is not mature enough, we have to face the problem that the network coverage is not comprehensive enough. In order to solve this problem, it is considered to use other networks to improve the coverage problem, and the global system for mobile communication (GSM) network is a supplement with the best cost performance. Therefore, currently, the applications of TD-SCDMA and GSM dual-mode mobile terminals are very common.
China mobile multimedia broadcasting (CMMB) employs the mobile TV reception standard STiMi autonomously developed by China. This standard is suitable for broadcast service frequencies in the range from 30 MHz to 3000 MHz, and a broadcast system which transmits multimedia signals such as TV, broadcast, data information and so on wirelessly through satellites and the ground can realize domestic roaming. CMMB is a special service of 3G applications, and due to the portability and applicability of the mobile terminal, CMMB TV has wider influence and application prospect than common TV. CMMB employs two sets of receiving systems to support U waveband (470 MHz-798 MHz) and S waveband (2635-2660 MHz) simultaneously, wherein U waveband receives signals from a ground forwarding network, and S waveband receives TV broadcast signals from satellites. Currently, mobile terminals with CMMB functions in China use U waveband.
CMMB antenna is an important constituent part of the air interface of a mobile terminal with the CMMB functions, and the function of the CMMB antenna is to complete the wireless communication between a CMMB mobile terminal and a transmitting station by receiving wireless signals from the transmitting station. The quality of the CMMB service depends to a certain extent on the performance of the CMMB antenna. Currently, the CMMB antenna commonly used in industry is external rod antenna. In the mobile telephone design, the external antenna is gradually replaced with embedded antenna. It is proven that with respect to the antenna efficiency which is the most critical electrical parameter to the application of the mobile terminal, an embedded antenna with good design can provide the same performance as the external antenna. At the same time, the requirements on a more fashionable appearance from the consumer further urge the mobile phone manufacturer to integrate the antenna inside the device. As compared to the external antenna, the embedded antenna has the same performance, better appearance characteristics and is more rigid, and therefore, the change from the external antenna to the embedded antenna has become an irreversible trend, and the embedding solution of the CMMB antenna and the application and development of the corresponding mobile terminal are also a trend.
However, the operating band of a dual-mode terminal (such as TD-SCDMA/GSM dual-mode mobile phone) is relatively wide, including bands such as GSM 900, DCS 1800, PCS 1900, TD 1.9G and TD 2.1G and so on. For reducing the interference among multiple antennas in the CMMB antenna embedding solution, improving the receiving sensitivity of the CMMB antenna, and ensuring good CMMB antenna receiving performance and so on, a reliable solution and implementation method are required.